Concentric cutting assembly, concentric cutting systems, and net penetration method

ABSTRACT

The problem of penetrating through nets and other objects is solved by cutting the object using concentric cutters in which a rotatable cutter having floating teeth rotates concentrically about a stationary cutter having fixed teeth. The object is cut by a severing action caused by the floating teeth of the rotatable cutter sliding against the fixed teeth of the stationary cutter. Embodiments of the invention include a UUV system for penetrating through fishing nets and other objects, concentric cutting assemblies for use in the UUV system and other systems, and a method for penetrating through fishing nets and other objects. A UUV system in accordance with an embodiment of the invention has a concentric cutting assembly at the forward end and a propulsor at the aft end. The concentric cutting assembly integrates seamlessly within the UUV housing and is deployed from the forward end of the UUV, enabling the UUV to quickly and efficiently penetrate through objects blocking its path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/720,057, filed May 22, 2015, which is a continuation of U.S. patentapplication Ser. No. 14/593,718, filed Jan. 9, 2015 (now U.S. Pat. No.9,061,361, issued Jun. 23, 2015), which is a divisional of U.S. patentapplication Ser. No. 14/156,697, filed on Jan. 16, 2014 (now U.S. Pat.No. 8,961,079, issued Feb. 24, 2015), which is a divisional of U.S.patent application Ser. No. 12/497,285, filed on Jul. 2, 2009 (now U.S.Pat. No. 8,714,889, issued May 6, 2014), the subject matter of each ofwhich are incorporated by reference in their entirety herein.

FIELD OF THE INVENTION

The invention relates generally to a cutting assembly, and in particularto a system, method, and apparatus for cutting nets and other objects.

BACKGROUND

The use of fishing nets and other objects in water bodies can present asignificant obstacle to marine vessels and underwater vehicles,especially in littoral zones where fishing activity is concentrated.Marine vessels and underwater vehicles can encounter fishing nets in avariety of orientations and tensions. Some nets are constructed with alight monofilament line and have simple square patterns. Other nets areconstructed with a heavy, braided line and have complex patterns. Netscan also be anchored and tightly strung, be loose and compliant, orfloat with weights distributed on the bottom.

Unmanned underwater vehicles (UUVs) have contributed greatly to thegathering of information in harbors and littoral waters where otherunderwater vehicles such as submarines cannot travel or be easilydetected. For example, UUVs can carry out critical missions in the areasof intelligence, surveillance, reconnaissance, mine countermeasures,tactical oceanography, navigation and anti-submarine warfare. Missionperformances, however, have been hindered by UUVs' inability topenetrate through fishing nets and other objects while travelingunderwater.

Presently, UUV mission areas are scanned for fishing nets and otherobjects. Mission routes are selected so as to minimize the probabilityof encountering objects even though the selected route may not be theshortest or the most desired route. Yet, UUVs may be called upon duringmission critical situations to penetrate waters in which there is a highprobability of encountering fishing nets and other objects. In thesesituations, a UUV may be forced to stop and maneuver around obstaclesencountered during its mission. If a UUV gets entangled in a fishingnet, divers may be required to retrieve the UUV and cause significantoperation delay. Operation failure may result if the UUV is notretrievable or lost altogether.

Accordingly, there is a need and desire for an apparatus, system andmethod for easily and quickly penetrating through nets and otherobjects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a UUV system in accordance with an embodimentdescribed herein.

FIG. 2A is an external view of a concentric cutting assembly inaccordance with an embodiment described herein.

FIG. 2B is an internal view of a concentric cutting assembly inaccordance with an embodiment described herein.

FIG. 3 is a profile view of a concentric cutting assembly in accordancewith an embodiment described herein.

FIG. 4 shows an inside view of a concentric cutting assembly inaccordance with an embodiment described herein.

FIG. 5 is a schematic diagram of an electronic assembly of a concentriccutting assembly in accordance with an embodiment described herein.

FIG. 6 is a flow chart of a method for penetrating through a net inaccordance with an embodiment described herein.

FIG. 7A illustrates a concentric cutting assembly in an armed state inaccordance with an embodiment described herein.

FIG. 7B illustrates a concentric cutting assembly in a deployed state inaccordance with an embodiment described herein.

FIG. 7C illustrates a deployed concentric cutting assembly cutting a netin accordance with an embodiment described herein.

FIG. 7D illustrates a concentric cutting assembly in a retracted statein accordance with an embodiment described herein.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof and illustrate specificembodiments that may be practiced. In the drawings, like referencenumerals describe substantially similar components throughout theseveral views. These embodiments are described in sufficient detail toenable those skilled in the art to practice them, and it is to beunderstood that structural and logical changes may be made. Sequences ofsteps are not limited to those set forth herein and may be changed orreordered, with the exception of steps necessarily occurring in acertain order.

The problem of penetrating through nets and other objects is solved bycutting the object using concentric cutters in which a rotatable cutterhaving floating teeth rotates concentrically about a non-rotatablecutter having fixed teeth. The object is cut by a severing action causedby the floating teeth of the rotatable cutter sliding against the fixedteeth of the non-rotatable cutter.

Disclosed embodiments include a system for penetrating through fishingnets and other objects, as well as various apparatuses including aconcentric cutting assembly for use in this system. Embodiments of theconcentric cutting assembly include an inside cutter rotatingconcentrically within an outside cutter, the inside cutter havingfloating teeth that slide against teeth fixed to the outside cutter.Further, disclosed embodiments include methods for penetrating throughfishing nets and other objects.

The invention may be used to particular advantage in the context ofunderwater vehicles traveling in areas with high fishing activity.Therefore, the following example embodiments are disclosed in thecontext of UUV systems. However, it will be appreciated that thoseskilled in the art will be able to incorporate the invention intonumerous other alternative systems that, while not shown or describedherein, embody the principles of the invention.

FIG. 1 shows a UUV system 130 in accordance with an embodiment describedherein. UUV 130 is integrated with a concentric cutting assembly 100 atthe forward end and a propulsor 140 at the aft end. UUV 130 may be, forexample, a modified ANT Glider Eyak 01 developed by Alaska NativeTechnologies, LLC or a modified Remus 600 developed by Hydroid, Inc. Inaccordance with an advantageous feature of this disclosed embodiment,concentric cutting assembly 100 integrates seamlessly within UUV housing110 as can be seen in FIG. 1. Seamless integration of concentric cuttingassembly 100 has the effect of minimizing drag as UUV 130 movesunderwater and the effect of minimizing the power required forconcentric cutting assembly 100 to penetrate through nets and otherobjects. In accordance with another advantageous feature of thisdisclosed embodiment, concentric cutting assembly 100 is deployed fromthe forward end of UUV 130, thus, enabling UUV 130 to quickly andefficiently penetrate through objects blocking its path.

FIG. 2A is an external view of concentric cutting assembly 100integrated into UUV 130 in accordance with the embodiment depicted inFIG. 1. FIG. 2B is an internal view showing the components insideconcentric cutting assembly 100 in accordance with the embodimentdepicted in FIG. 2A. Concentric cutting assembly 100 includes twoconcentric cutters: non-rotatable cutter 280 and rotatable cutter 290.Non-rotatable cutter 280 can be a composite cutter comprising outercylinder 210 and fixed teeth 240. Rotatable cutter 290 comprises innercylinder 220 and floating teeth 250.

Slide rails 200 are attached to the inside of UUV housing 110 as shownin FIG. 2B. Concentric cutters 280 and 290 move back and forth alongslide rails 200. Concentric cutters 280 and 290 move forward along sliderails 200 to engage and cut fishing nets and other objects encounteredby UUV 130 during a mission. After the object is cut, concentric cutters280 and 290 retract along slide rails 200 into their original positioninside UUV housing 110. Three slide rails 200 are used in the exampleembodiment of FIG. 2B. If desired, particular embodiments may optionallyinclude only two slide rails, more than three slide rails, or any othermeans for extending and retracting concentric cutters 280 and 290. Thoseskilled in the art will appreciate that alternative embodiments mayemploy roller bearings instead of slide rails. The roller bearings canbe contained within slots to prevent rotation of non-rotatable cutter280.

Outer cylinder 210 is mounted on slide rails 200. Inner cylinder 220rotates concentrically within outer cylinder 210. Six bearing plates 230are mounted to outer cylinder 210 (four of which are visible in FIG.2B). Bearing plates 230 serve two main purposes: (1) to keep concentriccylinders 210 and 220 axially aligned and (2) to keep floating teeth 250in constant contact with fixed teeth 240. Each bearing plate 230 can beadjusted in depth and tilt. If desired, particular embodiments mayoptionally mount bearing plates 230 to inner cylinder 220. Any desirednumber of bearing plates may optionally be used, however, the presentinventors have found that six bearing plates are effective in axiallyaligning concentric cylinders 210 and 220.

Concentric cylinders 210 and 220 of the disclosed embodiment are made ofcarbon fiber, however, cylinders 210 and 220 can be made of any othermaterial with properties similar to carbon fiber, such as, for example,titanium, stainless steel and carbon steel. The present inventors havefound that carbon fiber is sufficiently strong to be used forpenetrating nets and other objects and can be easily fabricated.

As shown in FIG. 2B, outer cylinder 210 can be formed with fixed teeth240 protruding from one end in a direction parallel to the center axisof outer cylinder 210. Fixed teeth 240 are each formed as blades havingsubstantially the same angled cutting edge as each other. According tothe embodiment of FIG. 2B, thirty-six fixed teeth 240 are evenly spacedabout outer cylinder 210. A cutting assembly embodying the principles ofthe invention can have any desired number of fixed teeth, however.Moreover, the fixed teeth can each have different shapes than shown, asis known in the art.

In accordance with an advantageous feature of the disclosed embodiment,three floating teeth 250 are spring-mounted about one end of the outersurface of inner cylinder 220. Similar to fixed teeth 240, floatingteeth 250 are formed as blades and have substantially the same angledcutting edge as each other. Further, floating teeth 250 extend frominner cylinder 220 along the same direction as fixed teeth 240 such thatthe blades of floating teeth 250 are parallel to the blades of fixedteeth 240.

The present inventors have discovered that three floating teeth areeffective at severing nets and other objects. Using a reduced number offloating teeth, compared to the number of fixed teeth, has two importantbenefits. First, a reduced number of floating teeth reduces the surfacecontact area formed by the floating teeth sliding against the fixedteeth, which produces less sliding friction between the cuttingsurfaces. Less sliding friction requires less torque and, thus, lesspower is required to run concentric cutting assembly 100. Second, peakpower consumption is minimized because the three floating teeth 250 canbe positioned around inner cylinder 220 such that no two pairs offloating teeth and fixed teeth are ever cutting at the same time.

Fixed teeth 240 and floating teeth 250 are fabricated from stainlesssteel in the embodiment of FIG. 2B. If desired, particular embodimentsmay optionally fabricate teeth from titanium, carbon steel, or any othermetal with properties similar to stainless steel. The inventors foundthat galling can roughen the contact areas between fixed teeth 240 andfloating teeth 250 after repeated use of concentric cutting assembly100. A lubricant such as AntiSeeze lube may optionally be placed betweenthe cutting surfaces to prevent material transferring from one surfaceto the other surface and to reduce friction. Alternatively, a cuttingsurface may be coated with a hardened material such as titanium nitride(TiN), titanium aluminum nitride (TiAN) or titanium carbon nitride(TiCN) to prevent material transfer. In addition, an anti-frictioncoating such as molybdenum sulfite (MoST) may be optionally placed overthe hardened material to reduce friction.

If UUV 130 does not have its own neutral buoyancy mechanism, particularembodiments may optionally include foam 260 for neutral buoyancy. Foam260 can be positioned in the center of inner cylinder 220 around centerpipe 270. If desired, foam 260 can alternatively be positioned in therear of concentric cutting assembly 100 if UUV 130 has a forward lookingsonar located in the center of inner cylinder 220.

FIG. 3 is a profile view of concentric cutting assembly 100 inaccordance with the embodiment disclosed in FIG. 2B. In accordance withan advantageous feature of the disclosed embodiment, concentric cuttingassembly 100 includes two thin-walled concentric cutters 280 and 290. Athinly profiled concentric cutting assembly 100 allows it to fit tightlybetween UUV housing 110 and a forward looking sonar, if one exists inUUV 130. Although concentric cutting assembly 100 is less than one inchthick in this example embodiment, it can be readily appreciated that thethickness of concentric cutting assembly 100 can be adjusted based onthe space constraints of the particular UUV system and other alternativesystems.

In accordance with another illustrative feature of the disclosedembodiment, floating teeth 250 are mounted to inner cylinder 220 usinglow profile springs 300. Wavy springs such as those manufactured bySmalley Steel Ring Company can be used to keep the cutting assemblyprofile narrow. The inventors have found that mounting floating teeth250 to inner cylinder 220 using springs 300 provide three main benefits.First, springs 300 keep the cutting surfaces formed by floating teeth250 and fixed teeth 240 tightly together. Tight cutting surfacesfacilitate quick and efficient cutting of nets and other objects.Second, springs 300 keep cylinders 210 and 220 tightly against eachother. Third, spring-mounted floating teeth 250 act like another set ofbearings to keep concentric cylinders 210 and 220 evenly apart andaxially aligned.

It will be appreciated that the size and shape of floating teeth 250 andfixed teeth 240 are not limited to the example embodiment depicted inFIGS. 2 and 3. In fact, any size and shape of floating teeth 250 andfixed teeth 240 can be used so long as each floating tooth 250 creates abi-directional shearing action when sliding against fixed teeth 240.Preferably, the blades of fixed teeth 240 have the same or substantiallythe same cutting angle. The present inventors have found that bladeswith a 30 to 70 degree angle, preferably a 55 degree angle, areeffective at cutting nets and other objects. It will be appreciated thatthe cutting angle may need to be adjusted based on the objects to bepenetrated. For instance, blades with wide cutting angles are moreeffective at cutting through thick fishing nets than blades withnarrower cutting angles. Moreover, the shearing action is more effectiveif the cutting surface consists of the entire edge of the blade. Thepresent inventors have also discovered that fixed teeth 240 with roundedtips have the advantageous features of capturing and holding the net inplace while also preventing the rounded tips from catching on the netitself as rotatable cutter 290 rotates to cut the object. In contrast,floating teeth 250 preferably have pointed tips for more effectivecutting.

Another advantageous feature of the disclosed embodiment is thatrotatable cutter 290 is free floating—supported only by means that keepit axially aligned with non-rotatable cutter 280. In the exampleembodiment depicted in FIGS. 2 and 3, non-rotatable cutter 280 iscylindrical conforming to the shape of UUV housing 110 in order forconcentric cutting assembly 100 to seamlessly integrate with UUV 130.However, it will be appreciated that rotatable cutter 290 may be shapedother than as a cylinder. If desired, particular embodiments mayoptionally include a rotatable cutter shaped as an equilateral triangle,square, Y-shaped, pentagon, or any other shape so long as the rotatablecutter can rotate concentrically within non-rotatable cutter 280 and bemounted with at least one floating tooth.

If desired, non-rotatable cutter 280 can have a non-cylindrical shape insystems in which the non-rotatable cutter does not have to conform tothe cylindrical shape of UUV system 130. In an alternative embodiment,for example, the concentric cutters can be comprised of two concentricequilateral triangles in which one, two, or three floating teeth aremounted to a respective corner of the rotatable triangular cutter, andbearing plates are aligned with the floating teeth for axially aligningthe concentric cutters. In yet another alternative embodiment, theconcentric cutters can be comprised of two concentric squares with oneto four floating teeth mounted to a respective corner of the rotatablesquare cutter. It will be appreciated by those skilled in the art that arotatable cutter embodying the principles of the invention can be anyshape as long as it can rotate concentrically about a non-rotatablecutter and has at least one floating tooth that is kept tightly againstat least one tooth fixed to the non-rotatable cutter.

Rotatable cutter 290 can rotate clockwise or counter clockwisecontinuously in one direction. Those skilled in the art will appreciatethat the direction of rotation does not matter as along as floatingteeth 250 slide against fixed teeth 240 to create a shearing action thatcuts fishing nets and other objects. In an alternative embodiment,rotatable cutter 290 can be configured to rotate in both directions. Forinstance, rotatable cutter 290 can alternate rotating clockwise andcounter clockwise for a pre-determined time period.

FIG. 4 shows an inside view of concentric cutting assembly 100 inaccordance with an embodiment described herein. A motor system housedwithin motor housing 430 provides the means to rotate inner cylinder220. The motor system may be, for example, the Maxon RE 40 brushed motorequipped with a planetary gearhead such as a Maxon GP 42 gearhead. Bymounting motor housing 430 to outer cylinder 210, rotatable cutter 290can start rotating at any position with respect to non-rotatable cutter280 and gain momentum before concentric cutting assembly 100 contacts anobject. Spur gear 420 is mounted to the output shaft of the planetarygearhead and mates with internal ring gear 410, which is mounted toinner cylinder 220.

Actuator 400 moves concentric cutters 280 and 290 forward through UUVhousing 110 to penetrate nets and other objects and retracts concentriccutters 280 and 290 after penetration. Actuator 400 may be, for example,a Firgelli Automations model ZYJ 05-11-12-3, which has a stroke lengthof 3″ and can move from fully retracted to fully extended in 1.5 secondsand provide up to 50 lbs of actuation force to outer cylinder 210.Alternatively, an Ultra Motion Digit HT17 High-Torque NEMA 17 steppermotor actuator (Part No. D-A.083-HT17-4-2NO-RBC4S/RBC4S-SUW), which hascomparable speed to the Firgelli actuator, can be used to supply up to40 lbs of actuation force to outer cylinder 210. One contact point ofactuator 400 is mounted to outer cylinder 210 while the other contactpoint of actuator 400 is mounted on the inside of UUV housing 110 asshown in FIG. 4. If desired, particular embodiments may optionallyinclude multiple actuators without significantly increasing the profileor thickness of concentric cutting assembly 100. The multiple actuatorscan be placed radially about outer cylinder 210 and UUV housing 110.

Concentric cutting assembly 100 requires a power source and a speedsignal to operate. Both the power source and the speed signal can besupplied by or be provided completely independent of UUV 130.

FIG. 5 is a schematic diagram of an electronic assembly of concentriccutting assembly 100 in accordance with an embodiment described herein.Power is required to run the electronics housed in electronics housing500. Concentric cutting assembly 100 can be configured to utilize thebattery typically used by UUV 130 to power propulsor 140 to power itsown electronics. Electronics housing 500 contains microcontroller 530,DC-DC converter 510, motor relay 520 and actuator controller 540. Asshown in FIG. 2B, UUV housing 110 has a recess at the rear of concentriccutting assembly 100. This recess is deep enough to fit electronicshousing 500.

Microcontroller 530 controls concentric cutting assembly 100 functionsincluding setting a cutter deployment speed for the speed at whichconcentric cutters 280 and 290 are deployed, a cutter run time for thelength of time that rotatable cutter 290 rotates at full speed, and acutter retrieval time for the length of time it takes to retractconcentric cutters 280 and 290 after cutting.

Preferably, components such as motor housing 430, actuator 400 andelectronics housing 500 are made waterproof. In this disclosedembodiment, actuator 400 is waterproofed using a silicone rubber boot.Further, motor housing 430 is machined from PVC with a double “O” ringshaft seal. All housing joints are double sealed to protect againstwater infiltration. Surrounding electronics housing 500 are fourwaterproof connectors 550. One waterproof connector is located on eachside of electronics housing 500.

FIG. 6 is a flow chart of a method for penetrating through a fishing netin accordance with an embodiment described herein. At step 600,microcontroller 530 waits for a speed signal from UUV 130. It should beappreciated by those skilled in the art that the speed signal can begenerated by UUV 130 using any known method of speed detection. Speedsensors such as a pressure switch or a paddle wheel can be used tomeasure the speed at which UUV 130 is traveling.

According to the disclosed embodiment, UUV 130 is configured to travelat 3.0 knots when carrying out a mission. An arming threshold speed canbe set at any speed between 0 and 3 knots, preferably 2.5 knots, for thepurpose of determining when to arm concentric cutting assembly 100.

Upon receiving a speed signal from UUV 130, microcontroller 530determines at step 610 whether UUV 130 is traveling at a speed above thearming threshold speed. Concentric cutting assembly 100 remains disarmeduntil UUV 130 reaches the arming threshold speed of 2.5 knots. If thespeed signal value is above the arming threshold speed, microcontroller530 sends a control signal to arm concentric cutting assembly 100 atstep 620, if it is not already armed. FIG. 7A illustrates concentriccutting assembly 100 in an armed state with concentric cutters 280 and290 inside UUV housing 110. The method returns to step 600 to wait forthe next speed signal from UUV 130.

When UUV 130 detects an obstacle in its path, its speed will decrease.The same speed sensor used by UUV 130 to measure its speed can also beused for object detection. For instance, when UUV 130 comes into contactwith an obstruction, its speed will decrease. Speed changes can bemeasured and provided to microcontroller 530. A cutting activationthreshold speed can be set for the purpose of determining when to deployconcentric cutting assembly 100. It should be appreciated by thoseskilled in the art that UUV 130 can employ any known method of objectdetection. At step 630, microprocessor 530 determines whether UUV 130 istraveling at a speed below the cutting activation threshold speed of 2.0knots.

If UUV 130 is traveling at a speed below the cutting activationthreshold speed, microcontroller 530 determines whether concentriccutting assembly 100 is armed at step 635. Microcontroller 530 sends acontrol signal to deploy concentric cutters 280 and 290 at step 640 ifconcentric cutting assembly 100 is armed. During deployment, concentriccutters 280 and 290 extend out of the forward end of UUV 130 along sliderails 200 as shown in FIG. 7B. At the same time, rotatable cutter 290starts rotating, preferably in a counter clockwise direction. Rotatablecutter 290 is also preferably rotating at full cutting speed by the timenon-rotatable cutter 280 comes into contact with fishing net 750. Inthis disclosed embodiment, rotatable cutter 290 has a full cutting speedof 100 revolutions per minute (RPM).

At step 650, concentric cutting assembly 100 penetrates through fishingnet 750 using concentric cutters 280 and 290. Non-rotatable cutter 280captures and holds net 750 using at least one fixed teeth 240. Thepresent inventors have discovered that holding the net or other objectin place using non-rotatable cutter 280 has two primary benefits. First,UUV 130 is held still with respect to net 750. In other words, rotatablecutter 290 will not cause UUV 130 to rotate. Second, net 750 is heldtaut which facilitates quicker and easier cutting.

Rotatable cutter 290 rotates for a predetermined length of time,preferably 6 seconds. The length of time should be sufficient for UUV130 to penetrate net 750 using the shearing action caused by floatingteeth 250 sliding against fixed teeth 240. It will be appreciated thatthe direction of rotation can be clockwise or counter clockwise so longas a bi-directional shearing action results from the rotation. FIG. 7Cshows concentric cutting assembly 100 using cutters 280 and 290 topenetrate through fishing net 750.

UUV 130 continues with its mission after cutting net 750. At step 660,concentric cutters 280 and 290 retract into their original positionsinside UUV housing 110 along slide rails 200. If desired, concentriccutting assembly 100 may optionally be disarmed at step 660. The processreturns to step 600 to wait for the next speed signal from UUV 130.

Disclosed embodiments will simplify and add flexibility to UUV missionplanning and execution. UUV operation remains essentially unchangeduntil an object is detected. Once the object is detected, the concentriccutting assembly will engage the object, penetrate the object, and allowthe UUV to carry out its mission with minimal loss of time. Disclosedembodiments allow a greater percentage of missions to be performed witha reduced risk of UUV loss or damage.

The foregoing merely illustrate the principles of the invention. Forexample, although the concentric cutters of the illustrative embodimentsconsist of a single non-rotatable cutter and a single rotatable cutter,it is possible for alternative embodiments to incorporate more than onestationary cutter and more than one rotating cutter. In addition,although the floating teeth of the illustrative embodiment have acertain shape, other shapes, materials and configurations are possible.In still other alternative embodiments, UUVs may require a completelyautonomous concentric cutting assembly. The concentric cutting assemblyin these alternative embodiments can be attached to the outer surface ofthe UUV and have a separate object detection sensor or speed sensor andan independent power supply. Although the invention may be used toparticular advantage in the context of UUVs, those skilled in the artwill be able to incorporate the invention into other underwatervehicles, marine vessels, and non-marine systems. It will thus beappreciated that those skilled in the art will be able to devisenumerous alternative arrangements that, while not shown or describedherein, embody the principles of the invention and thus are within itsspirit and scope.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. An underwater vehicle comprising: a cuttingassembly; and a cutting controller configured to: arm the cuttingassembly; detect an object in a path of the underwater vehicle; deploythe cutting assembly only if the cutting assembly is armed; and cut theobject as the cutting assembly contacts the object.
 2. The underwatervehicle of claim 1, wherein detect the object comprises being configuredto determine that a speed of the underwater vehicle is below apredetermined cutting activation threshold speed.
 3. The underwatervehicle of claim 1, wherein arm the cutting assembly comprises beingconfigured to generate and/or receive a control signal.
 4. Theunderwater vehicle of claim 1, wherein arm the cutting assemblycomprises being configured to determine that a speed of the underwatervehicle is above a predetermined arming speed.
 5. The underwater vehicleof claim 4, wherein the predetermined arming speed is between 0 andabout 3 knots.
 6. The underwater vehicle of claim 5, wherein thepredetermined arming speed is about 2.5 knots.
 7. The underwater vehicleof claim 4, further comprising a pressure switch and wherein the speedof the underwater vehicle is determined using the pressure switch. 8.The underwater vehicle of claim 4, further comprising a paddle wheel andwherein the speed of the underwater vehicle is determined using thepaddle wheel.
 9. An underwater vehicle comprising: a cutting assembly;and a cutting controller configured to: arm the cutting assembly; detectan object in a path of the underwater vehicle, wherein detect the objectcomprises being configured to determine that a speed of the underwatervehicle is below a predetermined cutting activation threshold speed;deploy the cutting assembly; and cut the object as the cutting assemblycontacts the object.
 10. The underwater vehicle of claim 9, wherein thespeed of the underwater vehicle is determined using a speed sensor. 11.The underwater vehicle of claim 9, wherein the speed of the underwatervehicle is determined using a control signal.
 12. The underwater vehicleof claim 1, wherein deploy the cutting assembly comprises beingconfigured to cause relative motion between an outer hull of theunderwater vehicle and the cutting assembly in a fore-aft direction. 13.The underwater vehicle of claim 1, wherein deploy the cutting assemblycomprises being configured to extend the cutting assembly toward theobject.
 14. The underwater vehicle of claim 13, wherein deploy thecutting assembly comprises being configured to extend the cuttingassembly on at least one slide rail toward the object.
 15. An underwatervehicle comprising: a cutting assembly comprising a plurality of teethformed on at least two concentric blades; and a cutting controllerconfigured to: detect an object in a path of the underwater vehicle;deploy the cutting assembly, wherein deploy the cutting assemblycomprises relative motion between at least two of the plurality of teethto create a cutting motion; and cut the object as the cutting assemblycontacts the object.
 16. The underwater vehicle of claim 15, wherein thecontroller is configured to sustain the cutting motion for apredetermined length of time.
 17. The underwater vehicle of claim 16,wherein the predetermined length of time is about 6 seconds.
 18. Theunderwater vehicle of claim 15, wherein the concentric blades alternaterotating clockwise and counter clockwise for a pre-determined timeperiod.
 19. An underwater vehicle comprising: a cutting assembly; and acutting controller configured to: detect an object in a path of theunderwater vehicle; deploy the cutting assembly; cut the object as thecutting assembly contacts the object; and retract the cutting assembly.20. The underwater vehicle of claim 19, wherein the controller isfurther configured to repeat the deploy the cutting assembly afterretracting the cutting assembly.